1. Technical Field of the Invention
The present invention relate s to a roller conveyor of the type installed on a ceiling or floor or built into a shelf facility. The present invention further relates to a roller shaft support that is used for such a roller conveyor and that is slidable and point installable within a side frame of the roller conveyor.
2. Description of Related Art
U.S. Pat. No. 5,582,286 (issued Dec. 10, 1996 to Kalm, et al.) discloses a conventional prior art structure for a roller conveyor. In accordance with this conventional structure, a conveyor section is configured by providing a plurality of linear or tapered drive/transfer rollers supported by and extending between a pair of longitudinally extending side rail housings. Articles to be transferred by the conveyor section move along a conveyor path whose extent and direction is defined by the side rail housings and supported rollers.
Each conveyor section has at least one operating region. An article detection sensor mounted within the side rail housing in each operating region functions to sense an article transferred along the conveyor path and generate a detection signal indicative thereof. A conveyor controller responds to the detection signal and actuates the drive rollers to move the detected article in a controlled fashion along the conveyor path.
Each side rail housing is substantially C-shaped in cross-section to define an interior chamber within which conveyor controllers, controller wiring and article detection sensors are mounted. A removable cover may be mounted to the side rail housing over its exterior facing opening to enclose the interior chamber. Since the article detection sensors, conveyor controllers, and connection wiring are all provided within the interior chamber of the side rail housing, management of this inside space becomes a significant concern and problem. The provision of a substantial amount of wiring along with the necessary controller and sensor components crowds the interior chamber making maintenance and inspection difficult tasks to accomplish. There is a need for different roller conveyor side rail housing to support easy management and configuration of detection sensors, conveyor controllers, and connection wiring.
The article detection sensor used in the prior art is typically one of the photo sensor/reflector variety. When such an article detection sensor is mounted within the interior chamber of the prior art C-shaped side rail housing, an opening must be formed within the wall of the housing to allow a detection light beam to pass. In the event the conveyor section should ever be reconfigured, or if the operating region(s) should be changed, it is likely that the positioning of the article detection sensor may also need to be changed. This inconveniently requires that a new opening be formed in the wall of the housing. It further requires that the article detection sensor be remounted within the cramped confines of the interior chamber of the side rail housing. In sum, it is difficult to change detection position and operating regions in prior art conveyor structures.
Such laterally projecting photo sensor/reflector type article detection sensors do not always provide error-free detection. The light from the sensor must be projected all the way across the width of the conveyor section. In instances where the conveyor is especially wide, inconsistent reflection may occur giving rise to erroneous article detections. A need exists for an alternative mechanism for mounting photo sensor/reflector type article detection sensors to achieve more accurate detection operation and support easy changes in positioning the detector and reconfiguration of operating regions.
To mount the individual drive/transfer rollers to the side rail housings, holes are typically formed in the wall of the side rail housing into which the shafts of each roller are inserted. Generally speaking, the cross-sectional shape of each roller shaft is polygonal. More particularly, an octagonal shape is conventionally used, but other polygonal or elliptical cross-sectional shapes may alternatively be used. The hole formed in the wall of the side rail housing has a polygonal shape corresponding to that selected for the roller shaft. In order to allow for easy insertion and extraction of rollers from the side rail frame, the holes on at least one side of the conveyor must be slightly larger than the shaft. As will be discussed in more detail below, sizing of shaft openings in the side frames can present significant concerns.
To assist in the insertion process, the shaft on one end of each roller is spring loaded. The non-spring loaded shaft end of the roller is first inserted (at an angle to the conveyor path) into the slightly larger one of the holes in the side rail housing. The shaft on the opposite end of the roller is then loaded, and the roller is moved into position between the side rail housings. Once aligned with the hole on the opposite side rail housing, the spring loaded shaft is released, thus completing roller installation.
During operation of the roller conveyor, the drive rollers are intermittently actuated in order to control the transport of articles along the conveyor path. This intermittent actuation causes the roller shaft to rock back and forth within the slightly oversized hole in the side rail housing. With enough instances of actuation and rocking back and forth, a rounding off of the polygonal shape of either (or both) the roller shaft or the side rail housing hole occurs. Eventually, this leads to failure and a complete replacement of the side frame. A need exists for a more stable and failure resistant roller shaft mounting assembly.
The use of holes formed in the side rail housings to support the plurality of drive/transfer rollers fixes the position, pitch and orientation of the rollers along the conveyor path. Each reconfiguration of the rollers along the conveyor path undesirably may require the forming of new holes in an existing side rail housing. In more dramatic reconfigurations, the formation of the required number of new holes in an existing side rail housing may be too difficult to implement. Alternatively, such newly formed holes may weaken the structural integrity of the side rail housing. Replacement of the side rail housings then becomes the only alternative. It is thus recognized that the prior art roller conveyor structure does not support easy roller reconfiguration (such as to accommodate changes in pitch or changes in roller diameter).
Japanese Patent Application (laid-open) No. 7-117832 discloses a roller conveyor with a side rail housing configuration and mechanism supporting roller pitch change. In accordance with this roller conveyor configuration, a multi-pitch bracket is provided on supporting side frames in such a way that the bracket is slidable in the longitudinal direction along the supporting frames. When a desired position of the bracket is reached, the bracket may be fixed to the frame. Each bracket includes a section for fitting roller shafts. Thus, following fixation of the bracket to the frame at the desired position, individual drive or transfer rollers may be installed in the shaft-fitting sections of the brackets to define the conveyor path.
In the event an individual one of the brackets breaks or otherwise needs to be replaced or moved (for example, when a pitch change is required), all of the rollers from that bracket to an end of a conveyor section must be removed, and each of their associated brackets must be slid out of the frame. This is necessary in order to gain access to the individual bracket which has been designated for replacement. Following replacement of the designated bracket, the previously removed brackets are then reinstalled, and the removed rollers are again positioned in the brackets to re-define the conveyor path. A better frame and bracket assembly is needed to provide for less cumbersome roller conveyor production and maintenance activities.
Another difficulty of this prior art roller conveyor configuration is that the disclosed bracket is formed in such a way as to support only linear rollers. In the event tapered rollers are specified for use in the designed roller conveyor, a different (tapered roller specific) bracket must be installed. Thus, in order to fully support variability in roller conveyor design and configuration, multiple brackets must be produced and properly selected for installation. There is accordingly a need for a linear or tapered roller supporting bracket that may be installed, removed and replaced without affecting neighboring brackets.